The present invention relates to a method according to the preamble of the appended claim 1, a communication device according to the preamble of the appended claim 7, and a communication system according to the preamble of the appended claim 10.
The term xe2x80x9cwireless communication systemxe2x80x9d refers generally to any communication system which enables wireless communication between a wireless communication device (MS) and the fixed parts of the system, when the user of the wireless communication device is moving within the service area of the system. A typical wireless communication system is a public land mobile network PLMN. The majority of wireless communication systems in use at the time of filing this application belong to so-called second generation mobile communication systems, of which the widely known GSM mobile communication system (Global System for Mobile telecommunications) can be mentioned as an example. The present invention is especially well applicable to third generation mobile communication systems currently under development. In this specification, a GPRS system (General Packet Radio Service) which is being standardized at present, will be used as an example of such a mobile communication system. It is obvious that the invention is also applicable in other mobile communication systems, in which it is possible to define different quality of service levels, or the like, for a data transmission connection.
The GPRS system defines the concept of bearer services. Generally it corresponds to the communication channel of prior systems, which is used to define e.g. a user data rate and quality of service (QoS), both provided by the system in the data transmission between a wireless communication device and some other part of the mobile communication network.
One of the most difficult functions of the bearer services is to provide a sufficient quality of service level reliably for each user. The general packet radio service GPRS is a new service under development for the GSM mobile communication system. The functional environment of the GPRS system comprises one or more subnetwork service areas, which are connected to form a GPRS backbone network. The subnetwork comprises numerous support nodes (SN), of which serving GPRS support nodes (SGSN) will be used as an example in this specification. The serving GPRS support nodes are connected to the mobile communication network (typically to a base station via an interface unit) in such a way that they can provide packet switching services for wireless communication devices via base stations (cells). The mobile communication network provides packet-switched data transmission between the support node and the wireless communication device. Different subnetworks are, in turn, connected to an external data network, for example to a public switched data network (PSDN), via GPRS gateway support nodes (GGSN). Thus, the GPRS service enables packet-format data transmission between a wireless communication device and an external data network, wherein certain parts of the mobile communication network form an access network.
In order to use the GPRS services, the wireless communication device first performs a GPRS attach, with which the wireless communication device indicates to the network that it is ready for packet data transmission. The GPRS attach establishes a logical link between the wireless communication device and the support node SGSN, and thereby allows short message services (SMS) via the GPRS network, paging services via the support node, and notifying the wireless communication device of incoming packet data. Furthermore, in connection with the GPRS attach of the wireless communication device, the support node provides a mobility management function (MM) and performs user authentication. To transmit and receive information, a packet data protocol (PDP) is activated, with which a packet data address to be used in packet data connection is defined for the wireless communication device, wherein the address of the wireless communication device is known in the gateway support node. Thus, in the GPRS attach, a data transmission connection is established to the wireless communication device, to the support node and to the gateway support node, and a protocol (e.g. X.25 or IP), a connection address (e.g. X.121 address), a quality of service level, and a network service access point identifier (NSAPI) are defined for this connection. The wireless communication device activates the packet data connection with an activate PDP context request, in which the wireless communication device reports the temporary logical link identity (TLLI), the packet data connection type, the address, the required quality of service level, the network service access point identifier, and possibly also the access point name (APN).
The quality of service level defines, for instance, how packet data units (PDU) are processed in the GPRS network during transmission. For example the quality of service levels defined for the connection addresses are used to control the transmission order, buffering (packet queues) and discarding packets in the support node and in the gateway support node, especially when there are simultaneously two or more connections which have packets to be transmitted. Different quality of service levels define different delays for packet transmissions between different ends of the connection, different bit rates and the number of discarded packet data units can vary in connections of different quality of service level.
For each connection (connection address), it is possible to request a different quality of service level. For example in e-mail connections, a relatively long delay can be allowed in the message transmission. However, interactive applications, for example, require high-speed packet transmission. In some applications, as in file transfer, it is important that the packet transmission is virtually flawless, wherein packet data units are re-transmitted in error situations, if necessary.
In the current GPRS system, the quality of service level profile contains five different parameters: service precedence, delay class, reliability, mean bit rate and maximum bit rate. Service precedence defines a kind of priority for the packets belonging to a certain connection. Delay class defines average and maximum delays for all the packets belonging to the same connection. Reliability defines whether in the data transmission an acknowledgement (ARQ) is used or not (no ARQ) in the logical link control layer LLC and in the radio link control layer RLC. Furthermore, reliability is used to define whether a protected mode is used in unacknowledged data transmission, and whether the GPRS backbone network uses the TCP or the UDP protocol when transmitting packets belonging to the connection. On the basis of these said parameters, four quality of service classes are established in the GPRS system, which define the quality of service provided by the LLC layer to the connection. These quality classes are distinguished by a special service access point identifier (SAPI).
The appended FIG. 1 presents the function of a known LLC protocol layer 101 in a wireless communication device and in a GPRS support node. Block 102 illustrates the functions of a known RLC/MAC (Radio Link Control/Media Access Control) layer, which are necessary between the LLC layer 101 and the wireless communication device (not shown). Correspondingly, block 103 illustrates the functions of a known BSSGP (Base Station Subsystem GPRS Part) layer, which are necessary between the LLC layer 101 and the nearest serving GPRS support node (not shown). The interface between the LLC layer 101 and the RLC/MAC layers is called the RR interface, and the interface between the LLC layer 101 and the BSSGP layers is called the BSSGP interface.
Above the LLC layer 101, there are known GPRS mobility management functions 104, SNDCP functions 105, and short message service functions 106, which all belong to a layer 3 in the presented layer structure. Each one of these blocks has one or more interfaces to the LLC layer 101, for coupling to the different parts of the same. Logical link management block 107 has an LLGMM control interface (Logical Linkxe2x80x94GPRS Mobility Management) to the block 104. The mobility management data is routed via the LLGMM interface between the block 104 and the first LLE block (Logical Link Entity) of the LLC layer. The second 109, third 110, fourth 111, and fifth 112 LLE block connect to block 105 via corresponding couplings. Terms QoS 1, QoS 2, QoS 3, and QoS 4 are also used for these blocks according to the quality of service level of the packets processed by these blocks. The sixth LLE block 113 of the LLC layer is connected to block 106 via an LLSMS interface (Logical Linkxe2x80x94Short Message Service). The service access point identifiers of the first 108, second 109, third 110, fourth 111, fifth 112, and sixth LLE block are 1, 3, 5, 9, 11, and 7, respectively. In the LLC layer, each one of these LLE blocks is connected to a multiplexing block 114 which processes connections via the RR interface to block 102, and further to the wireless communication device, as well as connections via the BSSGP interface to block 103 and further towards the support node SGSN.
The connection between the multiplexing block 114 and the lower layer block 102 in the direction of the wireless communication device is called a xe2x80x9ctransmission pipexe2x80x9d. Because all the packet flows between the upper parts of the LLC layer and lower layers 102 travel via the same multiplexing block 114 and transmission pipe, the quality of service level refers to this transmission pipe. When setting up a connection, resources are allocated for it in the mobile communication network in such a way that the quality of service level of the connection would be as close as possible to that requested. In the wireless communication device it is, however, possible to have several applications requiring packet data service running simultaneously. Consequently, certain resources are allocated for these applications, which resources, if divided among different applications, may cause problems in maintaining the quality of service level. For example, in case there are both real time applications and non-real time applications running simultaneously, for which the resources are allocated dynamically, the transmission of packets of a non-real time application also takes up resources from real time applications, whose quality of service level can thus be impaired, for instance due to transmission delays. This could be taken into account by allocating a fixed resource for the applications, but that, however, results in an unnecessary consumption of the resources of the mobile communication network.
The purpose of the present invention is to reduce the aforementioned drawbacks and to provide a more efficient method and system for allocating resources in packet-format data transmission. The invention is based on the idea that resources are allocated for an application either fixedly or dynamically, depending on the quality of service level required by the application. The method according to the invention is characterized in what will be presented in the characterizing part of the appended claim 1. The communication device according to the invention is characterized in what will be presented in the characterizing part of the appended claim 7. The communication system according to the invention is characterized in what will be presented in the characterizing part of the appended claim 10.
Considerable advantages are achieved with the present invention when compared with methods and systems of prior art. With the method according to the invention, it is possible to reliably ensure a certain quality of service level for each packet data application connection running in a wireless communication device, irrespective of the other connections active in the wireless communication device. Furthermore, the capacity of a mobile communication network provided with a packet data service can be used more effectively because there are no resources unnecessarily allocated.